Re: [Gimp-print-devel] Canon driver

[Robert L K. <rl...@al...>]

   Date: Mon, 08 May 2000 09:01:03 +0200
   From: Andy Thaller <th...@ph...>

   I've tested the canon driver's output this weekend, though not with
   every dither algorithm. 360x360 and 720x720 dpi seem fine, though
   slighty mistuned in respect to brightnes and contrast. 360x360 with
   variable dot sizes shows extreme color corruption (what can I do
   here?) and 1440x720 is way too dark.

1) For 1440x720, you need to divide v->density by 2.  Apparently the
Canon printers are like the Epson printers in this regard -- they're
really 720x720, and 1440 is done in two passes.

2) You probably want to fiddle with the_levels.

  double        the_levels[] = { 0.5, 0.75, 1.0 };

This indicates that there are three dot sizes, of size .5, .75, and
1.0 respectively.  However, I doubt that those being a bit off would
cause even moderately severe color corruption.  Most likely the format
of the output is wrong.  The dither routine normally generates the
output as concatenated rows, with the lowest bit plane first.  It's
possible (by means of dither_set_c_ranges and such) to change that
ordering around.  If Canon takes each pixel as a full unit, you need a
folding routine like that in print-escp2.c

   Given my current schedule I won't have much time within the next
   two months to fiddle around with the settings. So Robert, since I
   seem to be the only canon-user on this list (tell me if I'm wrong)
   we should consider to post some kind of job-announcement on
   sourceforge? At least you mentioned the possibility somewhere.

I'm not aware of any other Canon users.  Want me to post a job
announcement?

-- 
Robert Krawitz <rl...@al...>      http://www.tiac.net/users/rlk/

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lp...@uu...
Project lead for The Gimp Print --  http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton